Biology: Cell Types and Functions

Starter Activity

• Students need to answer a question.
• The answers are written on mini white boards.

Mitochondria

• Known as the powerhouse of the cell.
• Releases energy through respiration.
• Contains DNA, controlling cell activities.
• Responsible for protein synthesis.
• Found in all prokaryotes but only some eukaryotes.
• Present in plant cells, algae, and some prokaryotes.

Learning Objectives

• Understanding specialised cells and magnification calculations.
• Describing how specialised cells are adapted to their function.

Cell Types (Images)

• Diagrams show a phagocyte and a lymphocyte.
• Labelled parts include the nucleus and cytoplasm.

Red Blood Cells

• Structure:
  • Biconcave shape for greater surface area (diffusion of oxygen).
  • Contains haemoglobin (carries oxygen).
  • Lacks a nucleus (maximizes space for haemoglobin).
  • Flexible shape to fit through capillaries.
• Function:
  • Carry oxygen from lungs to body, and carbon dioxide back to lungs.

Phagocyte

• Structure:
  • Flexible shape to engulf microorganisms.
  • Lobed nucleus.
• Function:
  • Found in blood.
  • Attracted to diseases, bacteria.
  • Engulfs bacteria/pathogens, preventing infection.

B Lymphocyte

• Structure:
  • White blood cell with surface receptors.
• Function:
  • Produces antibodies to destroy pathogens (recognising antigens).
  • Reproduces rapidly, making copies of antibodies to neutralize pathogens.

Neuron

• Structure:
  • Elongated cells (long cells).
  • Branches at both ends to connect to other nerve cells.
  • Long axon (main branch) covered in myelin sheath (fat) - preventing electrical impulses from affecting surrounding parts of the body.
• Function:
  • Carry nerve impulses throughout the body.

Sperm Cell

• Structure:
  • Long tail for movement.
  • Enzymes (acrosome) to penetrate the ovum.
  • Many mitochondria for energy.
  • Made in male testes.
• Function:
  • Carry genetic material (DNA) to fertilize the egg.

Root Hair Cell

• Structure:
  • Large surface area to absorb water.
  • Thin cell wall for easy water passage.
  • Lacks chloroplasts.
  • May contain many mitochondria for active transport of mineral ions.
• Function:
  • Absorbs minerals and water from soil.

Palisade Cell

• Structure:
  • Tall shape with large surface area to capture sunlight.
  • Packed with chloroplasts for photosynthesis.
  • Located beneath the epidermis to allow light passage.
  • Regular shape for packing in a small area.
• Function:
  • Perform photosynthesis.

Ciliated Cell

• Structure:
  • Lines air passages and oviducts.
  • Tiny hairs (cilia).
• Function:
  • Prevents lung damage.
  • Moves mucus with trapped dust/bacteria to throat for swallowing.
  • Smoking can damage cilia and affect mucus removal.

Ovum (Egg Cell)

• Structure:
  • Cytoplasm with organelles.
  • Protective coat.
• Function:
  • Energy source for developing embryo.
  • Contains mother's genetic material for fertilization.

Rods and Cones

• Structure (Rods and Cones):
  • Outer segments contain photosensitive chemicals.
  • Nucleus present.
• Description includes differences:
  • specialized receptors in the eye

Guard Cells

• Structure:
  • Contain chloroplasts.
  • Thin outer wall, thick inner wall.
  • Control the opening and closing of stomata (pores in leaves).
• Function:
  • Regulate gas exchange and water loss in plants.

Magnification Calculations

• Formula: Magnification = Size of image / Actual size of specimen.
• Triangle diagram to illustrate the relation between these factors.
• Methods to convert between units (e.g., mm, μm, nm)
• Examples: Conversion between units to convert a size.

Additional Information: Microscopy units

• There are three units: millimetre (mm), micrometre (μm), and nanometre (nm).
• Conversion factors: 1 metre = 1000 mm, 1 mm = 1000 μm, 1 μm = 1000 nm
• Instructions to multiply/divide based on the conversion.

This quiz focuses on cellular structures and their specialized functions, highlighting the role of mitochondria, red blood cells, and immune cells. Students will explore the adaptations of these cells and practice magnification calculations. Test your understanding of cellular biology through engaging questions and diagrams.